1. Technical Field
This application generally relates to data storage, and more particularly to techniques used in connection with logical data objects and corresponding physical storage locations.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
A host may utilize logical data objects to represent one or more locations of a data storage system. Logical data objects may correspond, for example, to files or other entities as referenced and used on the host. Each logical data object may be mapped to one or more related storage locations of the data storage system. Different techniques may be used in connection with logical data objects used by a host system. One technique provides for determining the corresponding physical storage locations for a given logical data object. For example, a file may be specified and the disk and disk locations associated with the file may be determined.
It may be desirable to perform a mapping process which can be characterized as the reverse of the foregoing. In such a mapping process, one or more storage locations may be specified and one or more corresponding host-side logical data objects determined.